Is Ghost of Tsushima based on a true story?

It is based on the real history of the Mongolian invasion of Japan, which happened twice.

In both instances, the Mongolians lost.
The Mongolians were basically wiping the Japanese out while on land, since they were the most fierce and advanced military force on land in the world at that time with top quality armour and tactics. But once at night the Mongolians went back to the ships and met a shipwreck which was said to be caused by a storm. This happened in both invasions.

Yet, the story inside the game is mostly fictional.